Integration Challenges of Nanoporous Low Dielectric Constant Materials

Kim, Taek‐Soo; Dauskardt, R.H.

doi:10.1109/tdmr.2009.2033670

Cited by 14 publications

(3 citation statements)

References 42 publications

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“…Porous organosilicate (pSiCOH) materials are widely used as the low- k interlayer dielectric (ILD) materials for copper interconnect structures in advanced integrated circuits. − Low- k dielectrics with high volume percent porosity, however, typically have low Young’s modulus and fracture toughness, which can lead to thin film cracking and delamination during chemical mechanical polishing and packaging. − Moreover, plasma treatment and wet chemical treatment during back-end of line processing have been found to degrade the dielectric properties of pSiCOH materials and the interconnect leakage current. − …”

Section: Introductionmentioning

confidence: 99%

Nondestructive in Situ Characterization of Molecular Structures at the Surface and Buried Interface of Silicon-Supported Low-k Dielectric Films

et al. 2015

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As low-k dielectric/copper interconnects continue to scale down in size, the interfaces of low-k dielectric materials will increasingly determine the structure and properties of the materials. We report an in situ nondestructive characterization method to characterize the molecular structure at the surface and buried interface of silicon-supported low-k dielectric thin films using interface sensitive infrared-visible sum frequency generation vibrational spectroscopy (SFG). Film thickness-dependent reflected SFG signals were observed, which were explained by multiple reflections of the input and SFG beams within the low-k film. The effect of multiple reflections on the SFG signal was determined by incorporating thin-film interference into the local field factors at the low-k/air and Si/low-k interfaces. Simulated thickness-dependent SFG spectra were then used to deduce the relative contributions of the low-k/air and low-k/Si interfaces to the detected SFG signal. The nonlinear susceptibilities at each interface, which are directly related to the interfacial molecular structure, were then deduced from the isolated interfacial contributions to the detected SFG signal. The method developed here is general and demonstrates that SFG measurements can be integrated into other modern analytical and microfabrication methods that utilize silicon-based substrates. Therefore, the molecular structure at the surface and buried interface of thin polymer or organic films deposited on silicon substrates can be measured in the same experimental geometry used to measure many optical, electrical, and mechanical properties.

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Section: Introductionmentioning

confidence: 99%

Nondestructive in Situ Characterization of Molecular Structures at the Surface and Buried Interface of Silicon-Supported Low-k Dielectric Films

et al. 2015

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“…One key reliability issue found in the integration of low- k dielectrics has been delamination that occurs at low- k interfaces during fabrication, reliability testing, or packaging due to weak interfacial adhesion strength . In particular, the interface between low- k dielectrics and dielectric diffusion caps (e.g., SiCNH) has been reported to have weak adhesion strength. , Grill et al reported that the weak adhesion strength at a SiCOH/SiCNH interface was caused by a thin layer of SiCOH near the SiCOH/SiCNH interface that had a weaker cohesive strength than the bulk SiCOH .…”

Section: Introductionmentioning

confidence: 99%

Plasma Treatment Effects on Molecular Structures at Dense and Porous Low-k SiCOH Film Surfaces and Buried Interfaces

et al. 2015

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The effects of oxygen plasma treatment on molecular structures at low-k organosilicate (SiCOH) film surfaces and buried interfaces were investigated using sum frequency generation (SFG) vibrational spectroscopy and Raman spectroscopy. SFG and Raman spectra were acquired from pristine and plasma-treated low-k SiCOH films to characterize the interfacial and bulk molecular structures of the films before and after plasma treatment. Two SiCOH films with similar molecular structures but different porosities were investigated to correlate the effects of plasma treatment to the porosity of low-k films. SFG spectra indicated that the surface molecular structure of dense SiCOH films was more resistant to plasma damage than the surface molecular structure of porous SiCOH films. Furthermore, the ratio of SFG peak intensities before and after plasma treatment enabled quantification of methyl depletion at the surface of SiCOH films after plasma treatment. The molecular structure at buried Si/SiCOH interfaces was characterized by simulating SFG spectra from pristine and plasma-treated SiCOH films. SFG spectra from plasma-treated low-k films were simulated by adjusting the methyl orientation and number density parameters at the low-k/air interface to match experimental results. Simulated SFG spectra indicated that methyl groups at the buried interface of both dense and porous SiCOH films were oriented with a high tilt angle before and after plasma treatment. The developed methodology is general and can be extended to characterize the effects of many different plasma treatments, wet chemical treatments, and surface repair treatments on the interfacial molecular structures of many polymer or organic films.

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“…[3][4][5] Moreover, due to the intrinsic tensile stress and increased coefficients of thermal expansion of low-k dielectrics compared to SiO 2 , thin film cracking and adhesion are serious thermal-mechanical reliability issues for low-k dielectric materials. 6,7 Thermo-mechanical deformation of the package during package assembly and subsequent reliability tests can induce large local stresses that can initiate and propagate cohesive and/or adhesive cracks in different BEOL layers. 8 Therefore, a careful characterization of the mechanical stability of potential future low-k candidates is required to integrate these materials and Cu interconnects and assures reliability during chip packaging and under field conditions.…”

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confidence: 99%

In-situ scanning electron microscopy study of fracture events during back-end-of-line microbeam bending tests

Vanstreels¹,

Wolf

Zahedmanesh³

et al. 2014

Applied Physics Letters

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Integration Challenges of Nanoporous Low Dielectric Constant Materials

Cited by 14 publications

References 42 publications

Nondestructive in Situ Characterization of Molecular Structures at the Surface and Buried Interface of Silicon-Supported Low-k Dielectric Films

Nondestructive in Situ Characterization of Molecular Structures at the Surface and Buried Interface of Silicon-Supported Low-k Dielectric Films

Plasma Treatment Effects on Molecular Structures at Dense and Porous Low-k SiCOH Film Surfaces and Buried Interfaces

In-situ scanning electron microscopy study of fracture events during back-end-of-line microbeam bending tests

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